powercp-linux cross GCC 4.2 vs GCC 4.0.0: -Os code size regression?

[Duncan Sands]

Hi,

> I'm using the ppc-linux gcc-4.2.2 compiler and noted the code
> size have increased significantly (about 40%!), comparing with
> old 4.0.0 when using the -Os option. Same code, same compile-
> and configuration-time options. Binutils are differ
> (2.16.1 vs 2.17.50), though.

what LLVM version is old 4.0.0?  Are you compiling C++ (I don't know
what CSiBE is)?  Are you using exception handling?

> I've looked at the CSiBE testing results for ppc-elf with -Os,
> comparing gcc_4_0_0 with mainline and found that the mainline
> actually optimizes better, at least for the CSiBE test environment.
> After some analysis I've came to the following results:
>   Number of packages in the CSiBE test environment: 863
>   N of packages where mainline GCC optimizes better:   290
>   N of packages where mainline GCC optimizes worse: 436

From these numbers it looks like llvm-gcc is better than mainline
most of the time.  However you say: "... found that the mainline
actually optimizes better".  Can you please clarify.

Best wishes,

Duncan.